These tugs don't need to lift anchors above the push knees or deck. When they are engaged in anchor work (for moving dredges), they hook into wire on anchor buoy Wire(which goes through buoy to anchor) and it is winched in enough to lift off the bottom. The tug proceeds as directed by the dredge, while dredge is slacking their winch wire. The tug then sets the anchor, and disconnects from the wire/buoy. After all anchors have been set, the dredge can move several hundred feet on its own by slacking some wires and tightening others.
If you see pipe laying barges, this is how they move the rig as the pipe is layed. Often these same dredges will have "spuds"also. The anchors work in water thaat is to deep for the spuds, or when they need to move in several directions frequently.
This style of tug with the long fore deck is known as a "lugger" tug. They are used in the Gulf coast frequently as multi purpse boats. When they don't have the a frame setup that this boat has they will put pipe, supplies or a 20' container box to resupply inshore oil rigs.
The tug that I run was built as an Anchor handler. Although we don't do much anchor handling lately. It did hold the record in the late 70's as doing the deepest/heaviest anchors in the Gulf of Mexico.
